(a) Field of the Invention
The invention relates to a frame rate up-conversion (FRC) technique, particularly to an image generating device with the function of detecting static texts and a method thereof.
(b) Description of the Related Art
The frame rate up-conversion (FRC) technique is used for increasing the frame rate of a video source and has been applied in various fields, such as low-bit network video transmission for bandwidth-saving, converting a video source with a frame rate of 25 Hz into a higher frame rate for reducing frame juddering, and applying in hold-type liquid crystal displays (LCD) for avoid frame blurring and achieving clear image quality.
Most of the frame rate up-conversion (FRC) techniques use motion estimation (ME) to calculate the motion vector of an object and perform motion compensation interpolation (MCI) to allocate the moving object in different frames. Most of the motion estimation techniques use a block matching estimation algorithm to calculate the motion vector having the minimum of the sum of absolute difference (SAD). However, in many circumstances, many motion estimation techniques are easily trapped in the minimum of a local SAD, that is, the motion vector having the minimum of a local SAD is not necessary to be the real motion vector of the object and even the motion vector having the minimum of a global SAD is not necessary to be the real motion vector of the object.
Furthermore, while the block matching estimation algorithm in the prior art is used to process estimation, the correct estimation for image signals including static texts, such as captions, signs, etc. cannot be made when the background of the image contains moving object(s). As shown in FIG. 1, the upper part of the figure shows a preceding frame F0 and the lower part shows a current frame F1. For the preceding frame F0 as an example, the label “T” indicates a static text and the label “B” indicates a background object, the label “Mv” indicates a motion vector. When the image changes from the frame F0 to F1, the block matching estimation algorithm in the prior art will estimate an incorrect motion vector Mv due to the motion of the background object “B”. Such incorrect estimation often results in static text juddering or moving with the moving object to thereby lower the image displaying quality.